1. Field of the Invention
This invention relates to improvement of probe circuit board used for tests of semiconductor devices especially during or after the production phase of large scaled integrated circuits LSIs.
2. Description of the Prior Art
With the remarkable progress in high density scales of semiconductor integrated circuits, more probes in higher densities and various probe-positioning are required to test semi-conductor devices.
A probe circuit board is generally made by fixing many probes, to a center portion of a through-holed printed-circuit board having a square shape. Molded insulating supporters are provided so that the probe heads orient downward from the probe board via ring-shaped supporting parts made of ceramic or aluminum material. FIGS. 3a and 3b illustrate cross sectional views of a conventional probe circuit boards all of which provide probes.
The cross section shown in FIG. 3a is a right half side of a conventional probe circuit board 31. In the probe circuit board 31, a probe 32 is tapered to narrow the head diameter as it approaches the head. Probe 32 is fixed to an insulator 34 by molding work to align probe 32 at approximately a 10.degree. angle with respect to circuit board 33. Insulator 34 is fixed under a central portion of the circuit board through supporting parts 35 made of ceramic or aluminum materials which function as an insulating spacer.
Probe 32 is bent so that a head 32a is perpendicular to circuit board 33 when circuit board 33 is placed parallel to the ground.
In a probe circuit board 36 illustrated in FIG. 3b, a probe 37 is fixed perpendicular to an insulator 39 by way of molding so that probe 37 is perpendicular to circuit board 38 when circuit board 38 is placed parallel to the ground. Insulator 39 is fixed to circuit board 38 through supporting parts 40.
Semiconductor integrated circuits are tested by raising an inspection table 42 holding an IC chip 41 towards probe circuit board 31. Each head 32a of probe 32 touches each terminal 43 of the semiconductor integrated circuits to be tested.
As illustrated in FIG. 3a, at the moment in which head 32a of probe 32 touches terminal 43 of chip 41, head 32a of probe 32 tends to slide slightly on terminal 43. This is illustrated with double-chained lines in FIG. 4 which shows the movement of probe 32. With this sliding action a better contacting is expected, however, in case where terminal 43 is small, head 32a of probe 32 will slip out of terminal 43. In order to prevent this drawback, the amount of the sliding movement must be limited to a certain acceptable level.
On probe circuit board 36 providing probe 37 which has the construction illustrated in FIG. 3b, each probe 37 is arranged to be perpendicular to circuit board 36 and thereby allows for high density chip testing. When a head 37a of probe 37 makes contact with terminal 43 of chip 41, probe 37 is unable to use its own elasticity. Therefore, head 37a slips out of terminal 43 of chip 41 due to the force of contact between head 37a and terminal 43. It should be appreciated that under this condition all the probe heads 37a are not correctly aligned with respective terminals 43. Therefore, when inspection table 42, holding chip 41, is raised upward with a strong driven power towards probe board 36, probe head 37a makes contact with respective terminals 43. Unfortunately, probes 37 are forced to bend which results in neighboring heads touching each other as illustrated with the double-chained lines in FIG. 4b. Accordingly, it is required to improve these shortcomings by controlling head bending to acceptable levels.
The aim of this invention is to offer a guide-mask probe circuit board featuring that all the probe heads are always correctly arranged to the predetermined positions in order to minimize slipping movement and bending of the probe heads out of terminals of IC chips to be tested.